/*=========================================================================
 *
 *  Copyright RTK Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/

#ifndef rtkSoftThresholdTVImageFilter_hxx
#define rtkSoftThresholdTVImageFilter_hxx

#include "math.h"

#include "rtkSoftThresholdTVImageFilter.h"

#include <itkImageRegionIterator.h>
#include <itkImageRegionConstIterator.h>
#include <itkProgressReporter.h>
#include <itkPixelTraits.h>

namespace rtk
{

template <typename TInputImage, typename TOutputImage>
SoftThresholdTVImageFilter<TInputImage, TOutputImage>::SoftThresholdTVImageFilter()
{
  m_RequestedNumberOfThreads = this->GetNumberOfWorkUnits();
  m_Threshold = 0;
}

template <typename TInputImage, typename TOutputImage>
void
SoftThresholdTVImageFilter<TInputImage, TOutputImage>::DynamicThreadedGenerateData(
  const OutputImageRegionType & outputRegionForThread)
{
  itk::ImageRegionConstIterator<TInputImage> InputIt;
  itk::ImageRegionIterator<TOutputImage>     OutputIt;

  InputIt = itk::ImageRegionConstIterator<TInputImage>(this->GetInput(), outputRegionForThread);
  OutputIt = itk::ImageRegionIterator<TOutputImage>(this->GetOutput(), outputRegionForThread);

  while (!InputIt.IsAtEnd())
  {
    using ValueType = typename itk::PixelTraits<typename OutputImageType::PixelType>::ValueType;
    ValueType TV = 0;
    for (unsigned int i = 0; i < ImageDimension; ++i)
    {
      TV += InputIt.Get()[i] * InputIt.Get()[i];
    }
    TV = sqrt(TV); // TV is non-negative
    ValueType ratio = NAN;
    ValueType temp = TV - m_Threshold;
    if (temp > 0)
      ratio = temp / TV;
    else
      ratio = 0;

    OutputIt.Set(ratio * InputIt.Get());
    ++InputIt;
    ++OutputIt;
  }
}

} // namespace rtk

#endif
